Indoor pools may offer water-lovers a welcome relief from cold or stormy weather, but maintaining an indoor pool can cause an unwelcome increase in energy costs.  Heat loss through evaporation accounts for a whopping 70% of the energy consumed by an indoor pool, according to the U.S. Department of Energy (DOE).  With evaporation left unchecked, other problems arise such as excess chemical consumption, an overabundance of humidity, and building maintenance problems related to humidity. 

Dealing with the humidity from an indoor pool means installing a ventilation system that replaces indoor air with unconditioned air from outside.  The cost of running such a ventilation system to keep humidity at bay can be steep.  But all of the problems associated with water evaporation from an indoor pool can be significantly reduced with the use of pool covers.

Pool covers reduce evaporation dramatically, and as a result, energy costs can be lowered by as much as 70%, according to the DOE.  Additionally, pool covers keep chemical consumption at a minimum, and humidity levels are kept in check.  Lower humidity levels reduce the need to ventilate the air, which decreases energy costs even further.

Use pool covers only when the pool is not in use.  Pool covers should be removed from a pool completely before swimmers enter the water.